Abstract: The strength of the moderator cell of cold neutron source(CNS) was analyzed under internal and external pressure. The analytical results show that local stress exceeds design stress, and original design of the moderator cell isn’t reasonable. The structure dimension of original design was revised, and the revised structure was analyzed and optimal project was proposed. The reinforced structure of moderator cell can meet the design requirement well. Therefore, the project provides valuable reference for factual design in engineering.